First the cost difference between the sheet goods and complete kits basically comes down to production and design cost on our end.
We are working on building a complete how-to installation guide for when someone purchases sheet goods. This is another few weeks away at least, but it is in the works. Just quickly though, the material cuts easily with wood working tools, a router does a very good job and leaves a clean edge. Various other saws and flooring knives can be used as well, but then the edges need to be cleaned up afterward and a belt sander does a good job of that. Anyone that has a rudimentary set of wood working tools can work with the material and build a good looking deck covering.
Our custom kits go through a three step design process to ensure you get a kit that fits perfectly. First we send out a templating kit with instructions and material. You send the completed template kit back to us, and we digitize it. We will then send you back a full scale paper printout to ensure we got all the measurements right or we can make any final adjustments at that time.
Then we CNC cut the pieces to ensure accuracy, and because our system of joining the pieces together requires very tight tolerances. All of our custom kits secure to the deck using dual lock fasteners from 3M that are recessed in to the material (and we recommend the same for those using sheet goods.) All of the panels used to create a full deck covering are removable and attach together via a mechanically locking lap joint to ensure even if you step right at the edge of one piece, both sides of the joint will compress equally.
Attached is a close up picture of one of our removable joints.
Installing the fasteners to the deck depends on the surface you are installing over, and we either use dual locks with a VHB adhesive backing when installing on a bare AL or fiberglass deck or a backing designed for use with epoxies if we are going over an existing non-skid.